Learn about this topic in these articles:

characteristics

Permafrost with no water, and thus no ice, is termed dry permafrost. The upper surface of permafrost is called the
permafrost table. In permafrost areas the surface layer of ground that freezes in the winter (seasonally frozen ground) and thaws in summer is called the active layer. The thickness of the active layer depends mainly on the moisture content, varying from less than a foot in...